Studies on the Release, Survival And Germination Of Conidia Of Phyllactinia Corylea (Pers.) Karst.
Date
1968-06
Authors
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Journal ISSN
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Publisher
University of Ghana.
Abstract
Conidia of P.corylea germinated best at 25 - 28˚c. and germinated
well, uniformly and at the same rate at any humidity from zero to 100% R.H., but poorly in liquid water. Germ tubes conidia germinating at lower humidities were short whilst those at high humidities were
fairly long. Approximately 30 per cent of both germinated and ungerminated conidia shrivelled when incubated. at 0% R.H. This value
decreased with rise in humidity to show shrinkage in only one per cent
of conidia held at 100% R.H.
The conidia had a brief latent period of germination of 2 - 3
hours. The germinating conidia usually produced a single germ tube
and occasionally two. Branching of germ tubes was rare on glass surface
but appressoria were freely formed. On the host (Carica papaya) leaf
surface the germ tubes grew randomly over the epidermis am equally
freely formed appressoria. The appressoria were either terminal,
intercalary or lateral. Germ tubes produced at lower humidities
collapsed and shrivelled within a few hours after emergence. All germ
tubes produced and held at 0% R.H. shrivelled in 11 hours and those at
80.3% R.H. in 30 hours. Those at 92, 96.9 and 100% R.H. showed 94.5,
25.0 and 20.2% of shrivelled germ tubes respectively in 48 hours.
The Conidia germinated better in light and produced longer germ
tubes but formed fewer appressoria than those incubated in darkness.
Conidia stored at 5˚c and at various relative humidities were
preserved longest at the higher humidities and died quickest at the
lower humidities. Longevity was however brief and did not exceed 20
days at any humidity.
Multicellular, non-branching conidiophores, commonly 300 u long,
arose perpendicularly from the superficial mycelium. Each was terminated by a generative cell which formed the conidia. Usually only
one mature conidium was distinguishable at the tip of the conidiophore.
Immediately after maturation of the conidium the generative cell bent
approximately at the middle while the two arms of the cell stood at
right angles. This movement loosened the attachment of the conidium
to the conidiophore and the conidium fell at the slightest disturbance.
The bent generative cell then abstricted the next conidia. In still
air conidial chains were readily formed. A few conidia germinated whilst
still attached to the conidiophore. The conidia matured predominantly
in the dark and heaviest crop of spores were obtained in the morning.
The rate of bending of the generative cell was the same at 20 and
28˚c., in light and in dark and at 76 and 100% R.H. The ourvature in
the generative cell remained unaltered in sucrose solutions and in water.
The generative cell was not phototropic Whilst the entire conidiophore
Description
M.Sc. Degree
Keywords
Germination, Phyllactinia Corylea (Pers.) Karst, Conidia, Survival